In a photolithography process, when manufacturing a semiconductor device, a resist pattern is formed on, e.g., a semiconductor wafer (hereinafter, simply referred to as a “wafer”) by performing a resist coating process, an exposure process, and a developing process in sequence. In the resist coating process, by coating a resist solution on the wafer, a resist film is formed on the wafer. In the exposure process, the resist film is exposed to light through a pattern, and in the developing process, the exposed resist film is developed.
In this photolithography process, various heat treatments are performed. Such heat treatments include a heat treatment (prebake) performed after the resist coating process, a heat treatment (post-exposure bake) performed after the exposure process, a heat treatment (post bake) performed after the developing process, and so forth.
In the heat treatments, the wafer is heated to a preset temperature ranging from, e.g., about 100° C. to about 350° C. In order to perform a subsequent process, the heated wafer needs to be cooled to a room temperature (e.g., about 23° C.). Therefore, a heat treatment device includes a heating plate for heating the wafer, a cooling plate for cooling the heated wafer, and a transfer device for transferring the wafer between the heating plate and the cooling plate.
As the transfer device for transferring the wafer between the heating plate and the cooling plate, there is known a structure having a movable cooling plate that is configured to receive the wafer transferred by an external substrate transfer device, transfer the received wafer to the heating plate, receive the heated wafer from the heating plate, and cool the heated wafer (see, for example, Patent Document 1).
Further, as another transfer device for transferring the wafer between the heating plate and the cooling plate, there is known a structure having two transfer arms for transferring the wafer between the heating plate and the cooling plate that are fixed (see, for example, Patent Document 2).
Patent Document 1: Japanese Patent Laid-open Publication No. 2010-232415
Patent Document 2: Japanese Patent Laid-open Publication No. 2007-096243
In Patent Document 1, however, one cooling plate corresponding to one heating plate is provided. A heating time (e.g., about 60 seconds) for the wafer on the heating plate is longer than a cooling time (e.g., about 15 seconds) for the wafer on the cooling plate. Accordingly, there exists a certain period during which the cooling process is not performed on the cooling plate. As a result, an operation rate and a throughput of the heat treatment device may be reduced.
Further, in Patent Document 2, the wafer is transferred between the heating plate and the cooling plate by using the two transfer arms. Since, however, the heated wafer is transferred to the cooling plate and the transferred wafer is cooled on the cooling plate and taken out of the heat treatment device, it is time-consuming. As a result, the operating rate and the throughput of the heat treatment device may also be reduced.